Workers use conventional load balancing mechanisms to handle equipment such as heavy air driven tools and to aid in placement for mounting parts in assembly line operations. These load balancing mechanisms supply supporting forces in a vertical direction to counter gravitational force for supporting a load and also structure to resist torque and vibration associated with tool operations. Typical load balancing mechanisms include a two-piece articulated arm of a straight cross section pivotally connected to a support post about which the arm is rotatable. The arm is pivotal for movement in a vertical plane and also rotatable about an axis of rotation horizontally displaced from an axis of the support post. A hinged connection allows the two sections of the arm to be selectively moved by a worker for placement of a load located at a distal end of one of the arms within the reach of the articulated arm.
In this conventional arrangement of the load balancing mechanism, deflection is created in the support post by the weight of the arm and is increased by the application of a load on the arm. This deflection establishes a home position, due to the combined effect of deflection of the axis of rotation and the axis of rotation being displaced from the axis of the support post, which is at a lowest elevational position for the arm about the post. The arm drifts to this home position if left uncontrolled or unattended. This drift is further exaggerated by the hinged construction of the articulated arm and makes controlling the arm mandatory.
The straight cross sectional shape of the articulated arm also necessitates applying a greater lifting force to the arm to counter the weight of a load applied to the end of the arm as the greatest bending movement occurs at the connection of the support post and arm.
U.S. Pat. No. 5,037,267, entitled Load Balancing Mechanism, hereby incorporated by reference, discloses an improved load balancing mechanism which overcomes the above noted deficiencies of conventional load balancing mechanisms. However, the improved load balancing mechanism is designed solely for manual use by a worker.
A problem with load balancing mechanisms designed solely for manual use is that too much time and energy is wasted. For instance, in automobile assembly operations for placing an automobile seat into an automobile frame, a worker initially uses the mechanism to pick up a seat from a supply line or pickup position. Then, the worker moves the mechanism away from the supply line towards the assembly line to position the seat adjacent an automobile frame on the assembly line. The worker then uses the mechanism to place the seat into the automobile frame. To repeat the process for the next automobile frame coming down the assembly line, the worker moves the mechanism back to the supply line adjacent the next seat coming down the supply line to use the mechanism to pick up that seat.
Time and effort could be saved if the mechanism automatically moved between a part pickup position where it retrieves a part, and an "operator" position, for example adjacent the assembly line; at which operator position the worker could take over and manually move the part carried by the mechanism to mount the part into an automobile body or the like.
Thus, what is needed is an improved load balancing mechanism which overcomes the deficiencies associated with conventional load balancing mechanisms and is designed for combined automated and manual use by a worker.